This invention relates to suction operated cleaners of the type which have been developed to clean domestic swimming pools.
Automatic pool cleaners, operated by the flow of water induced through the cleaner by the pump of the filtration plant, are now becoming well known. Some of these cleaners interrupt the flow of water through the cleaner to induce forces on the cleaner, and the flexible tube connecting it to the filter weir, to move the cleaner in random step-by-step fashion over the floor of the pool. Interruption of flow has been effected by the use of mechanical gates which intermittently block the flow of water through the cleaner to induce these forces. Flexible, tubular, radially contractable diaphragms have also been used to temporarily interrupt flow in order to create inertia caused by the columns of water. Finally, flexible, tubular radially contractable diaphragms have also been used to interrupt the flow of water through the pool cleaners. By making these interruptions of small duration it has been possible to have the cleaner traverse not only horizontal, but vertical submerged surfaces.
Examples of these types of cleaners are described, for example, in U.S. Pat. Nos. 4,351,077, 4,023,227 and 4,642,833.